1. Field of the Invention
The invention relates to railway cars and particularly a connection for joining the edges of the roof sheets to the walls of a railway car.
2. Description of the Prior Art
The prior art includes U.S. Pat. Nos. 782,979; 1,255,309; 1,230,720; 3,303,619 and 3,909,918.
U.S. Pat No. 3,909,918 discloses a structure and method for joining relatively light gauge sheet metal edges such as would be utilized in an automobile car door. U.S. Pat. No. 3,303,619 discloses a structure and method of joining the edges of the sheet metal used in forming the walls of an industrial oven.
U.S. Pat. No. 1,255,309 is typical of the prior art railway car patents. As best shown in FIGS. 1, 4 and 6 the sheet metal roof wraps down around and under the side flanges of the wall structure. However, it should be noted that there is no interlock feature and in this type of structure the sheet metal roof edge and the flange members are not load carrying members. E.g., as shown in FIG. 4 in the roof structure disclosed, the loads are carried by the side plate A, which is bolted to the bracket C by vertically and transversely extending bolts D and E. The sheet metal roof functions as a covering which overlaps the roof structure. U.S. Pat. Nos. 782,979 and 1,230,720 are similar to the patent discussed above.
The prior art also includes railway car roof sheets having edge portions which are bolted or welded to the flanges of the side plate. If the connection utilizes a bolt or rivet the holes are usually drilled prior to assembly. During assembly the holes in the roof sheet edge portion must be aligned with the holes in the adjacent flange. This is time consuming and requires relatively close manufacturing tolerances. If the connection utilizes a weld, typically the roof sheet edge portion would be welded to the upper surface of the side plate flange. This results in a longitudinally extending weld seam. During use a railway car is subjected to cyclical twisting about a longitudinal axis. This type of cyclical loading over long periods of time may result in failure of the weld at the points of maximum flexure of the vehicle. Weld failure diminishes strength and also increases the chances of leakage into the interior of the car.
The present invention is an improvement over the prior art.